Soybean (Glycine max), as an important oilseed crop, is constantly threatened by abiotic stress, including that caused by salinity and drought. bZIP transcription factors (TFs) are one of the largest TF families and have been shown to be associated with various environmental-stress tolerances among species; however, their function in abiotic-stress response in soybean remains poorly understood. Here, we characterized the roles of soybean transcription factor GmbZIP15 in response to abiotic stresses. The transcript level of GmbZIP15 was suppressed under salt- and drought-stress conditions. Overexpression of GmbZIP15 in soybean resulted in hypersensitivity to abiotic stress compared with wild-type (WT) plants, which was associated with lower transcript levels of stress-responsive genes involved in both abscisic acid (ABA)-dependent and ABA-independent pathways, defective stomatal aperture regulation, and reduced antioxidant enzyme activities. Furthermore, plants expressing a functional repressor form of GmbZIP15 exhibited drought-stress resistance similar to WT. RNA-seq and qRT-PCR analyses revealed that GmbZIP15 positively regulates GmSAHH1 expression and negatively regulates GmWRKY12 and GmABF1 expression in response to abiotic stress. Overall, these data indicate that GmbZIP15 functions as a negative regulator in response to salt and drought stresses.

Transcriptome analysis of young ovules points to a receptor-like kinase that is preferentially expressed in archesporial and megaspore mother cells and function

Kenaf (Hibiscus cannabinus L.) is an environmentally friendly, multipurpose fiber crop suitable for osmotic stress tolerance studies. However, the mechanisms of tolerance remain largely unknown. Here, we identified a stress-responsive HcWRKY50 gene from kenaf (Hibiscus cannabinus L.) and studied its function and tolerance under drought stress. HcWRKY50 is a nuclear-localized protein. The overexpression of HcWRKY50 in Arabidopsis showed higher drought tolerance, exhibiting increased root length and lateral root number, and reduced stomatal density compared with the control lines. The seed germination and seedling growth of HcWRKY50 transgenic plants showed less sensitivity to ABA but they became more sensitive to ABA in their stomatal aperture. Furthermore, qRT-PCR analysis revealed that HcWRKY50 regulated ABA signaling by promoting the expression of several key ABA-responsive and stress-responsive genes such as RD29B and COR47 in transgenic lines. Taken together, this study demonstrated that the kenaf transcription factor HcWRKY50 regulates seed germination and seedling growth and improves drought stress tolerance via an ABA signaling pathway.

Members of the EPIDERMAL PATTERNING FACTOR (EPF) and EPF-Like (EPFL) families perform diverse regulatory functions in plant tissue morphogenesis, controlling the development of stomata, awns, shoot apical meristems (SAMs), and inflorescences. Nevertheless, the biological functions of OsEPF/EPFL family members in mediating responses to biotic/abiotic stresses are not yet widely characterized. Here, we demonstrated abundant cis-acting elements in the putative promoters of OsEPF/EPFL genes, including those associated with dehydration-, MeJA-, MYB binding site for drought, stress-, and ABA-responsive element. We performed a systematic analysis of the expression patterns of all OsEPF/EPFL family members under heat, cold, drought, and salt stress treatments. Among these genes, OsEPFL9 and OsEPFL10 exhibited rapid and sustained up-regulation across all four stress conditions. Furthermore, the majority of OsEPF/EPFL members were up-regulated specifically in response to salt stress. In terms of biotic stress responses, OsEPF2/5/7/10 were rapidly induced as early as 12 h post-infection (hpi) with the rice blast pathogen (Magnaporthe oryzae). Functional validation further revealed that its deficiency causes increased sensitivity to both M. oryzae and Xanthomonas oryzae pv. oryzae (Xoo). Collectively, our research will provide significant insights into the multifunctional roles of the OsEPF/EPFL gene family, particularly in stress responses. This work also establishes a theoretical basis and scientific reference for the application of plant small secreted peptides (SSPs) in crop disease resistance breeding and stress tolerance improvement.